Key Takeaways
- • Marc Andreessen, co-author of the Mosaic browser and co-founder of Netscape, is a general partner of Andreessen Horowitz (a16z), the Silicon Valley venture capital firm he co-founded with Ben Horowitz in 2009.
- • Andreessen Horowitz began with $300 million in initial capital and grew to $2.7 billion under management across three funds within three years, according to Wikipedia's profile.
- • The firm has launched dedicated crypto funds, including a $2.2 billion fund in 2021 and a $4.5 billion fund in 2022, and a national-security-focused American Dynamism fund in 2023.
- • Forbes ranked Andreessen #2177 on its 2026 Billionaires list and estimated his net worth at $1.9 billion as of June 2026.
- • Andreessen Horowitz led a $2 billion seed round for Thinking Machines Lab in July 2025, the largest seed round on record, valuing the firm at $12 billion.
Summary
Marc Andreessen is an American venture capitalist and former software engineer best known as co-author of Mosaic, the first widely used web browser, and as co-founder of Netscape Communications. Profile sources describe his career as spanning software development, entrepreneurship and venture investing. According to Wikipedia, he developed Mosaic at the National Center for Supercomputing Applications at the University of Illinois, and Netscape later became the first successful commercial web browser.
After Netscape was acquired by AOL in 1999 for $4.3 billion, Andreessen co-founded Loudcloud with Ben Horowitz, later renamed Opsware. Hewlett-Packard acquired Opsware for $1.6 billion in 2007. He also co-founded Ning, which was sold to Mode Media for a reported $150 million in 2011.
In 2009, Andreessen and Horowitz launched Andreessen Horowitz, which has grown into one of the most prominent venture firms in the industry. The firm has backed companies including Facebook, Twitter, GitHub, Pinterest and Coinbase. Its crypto funds, its 2023 American Dynamism fund targeting defense and hard-tech sectors, and its 2025 lead on Thinking Machines Lab's $2 billion seed round reflect its expansion across these areas, according to sources cited in the profile.
Forbes estimated Andreessen's net worth at $1.9 billion as of June 2026 and ranked him #2177 on its 2026 Billionaires list. Wikipedia also reports that he became an advisor to Donald Trump in 2024. Sources describe Andreessen as a central figure in Silicon Valley venture capital, though the profile material available for this summary does not provide further detail on recent developments.
After Netscape was acquired by AOL in 1999 for $4.3 billion, Andreessen co-founded Loudcloud with Ben Horowitz, later renamed Opsware. Hewlett-Packard acquired Opsware for $1.6 billion in 2007. He also co-founded Ning, which was sold to Mode Media for a reported $150 million in 2011.
In 2009, Andreessen and Horowitz launched Andreessen Horowitz, which has grown into one of the most prominent venture firms in the industry. The firm has backed companies including Facebook, Twitter, GitHub, Pinterest and Coinbase. Its crypto funds, its 2023 American Dynamism fund targeting defense and hard-tech sectors, and its 2025 lead on Thinking Machines Lab's $2 billion seed round reflect its expansion across these areas, according to sources cited in the profile.
Forbes estimated Andreessen's net worth at $1.9 billion as of June 2026 and ranked him #2177 on its 2026 Billionaires list. Wikipedia also reports that he became an advisor to Donald Trump in 2024. Sources describe Andreessen as a central figure in Silicon Valley venture capital, though the profile material available for this summary does not provide further detail on recent developments.
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